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Unique Visitors = 1/10th of Unique IPs?
Max Fomitchev submitted a little blog entry where he proposes that the ratio of unique IPs to actual unique users is 10:1. This flies in the face of the numbers you usually see attached to these sorts of things. I'm not sure about the logic he uses to come up with these numbers either.
No, most of the major ISPs just have an agreement with someone like Level3.net that handles dialin for them, and they only do caching for customers who pay for "high speed dialup" which is to say browsing through caching proxies that degrade image quality in order to reduce bandwidth consumption due to page loads.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
AOL user's actual IPs do not change mid-session, but the web proxy server that is making requests on behalf of the user changes all the time; my server logs even show certain objects on a single page for the same user are requested by different cache-*.aol.com servers.
Lots of info about that is here.. including the proxy IP list, etc... http://webmaster.info.aol.com/proxyinfo.html they say specfically "When a member requests multiple documents for multiple URLs, each request may come from a different proxy server. Since one proxy server can have multiple members going to one site, webmasters should not make assumptions about the relationship between members and proxy servers when designing their web site."
It totally eliminates public caching (e.g. ISP caches). A waste of bandwidth, a waste of CPU, and slower speeds (it can be a lot faster for users to get stuff from an intermediate cache than from the origin server).
Also, this isn't an option for anybody using name-based virtual hosting, which is incredibly common. There have been specifications published for getting around this, but browser support isn't there yet.
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